1. Field of the Invention
A certain aspect of the present invention relates to a recording apparatus.
2. Description of the Related Art
In an inkjet recording apparatus, ink is jetted onto a recording medium on a platen from a recording head mounted on a carriage being moved back and forth in the main-scanning direction (the carriage moving direction) to form an array of dots on the recording medium. The recording medium is conveyed in the sub-scanning direction (a direction orthogonal to the carriage moving direction) by, for example, a conveying roller, and another array of dots are formed on the recording medium in the main-scanning direction. This process is repeated to form an image on the recording medium.
When a recording medium is conveyed using a conveying roller in such an inkjet recording apparatus, the distance (hereafter called the conveying distance) by which the recording medium is conveyed varies depending on various factors such as an assembly error of the conveying roller, eccentricity of the conveying roller, and types of the recording medium. If the conveying distance is not constant, dots may be formed in a position different from the intended (ideal) position on the recording medium.
Japanese Patent Application Publication No. 2007-261262 discloses a technology intended to solve the above problem. In the disclosed technology, a test pattern is formed on a recording medium, a positional error of a recording medium in the sub-scanning direction (conveying direction) is detected based on the test pattern, and the amount of rotation of the conveying roller is corrected based on the detected positional error.
However, in the disclosed technology, the test pattern itself becomes inaccurate if a recording head for forming the test pattern includes clogged nozzles and/or skewed nozzles. If a positional error of a recording medium is detected based on an inaccurate test pattern, it is not possible to accurately correct the amount of rotation of the conveying roller.